Fig. 1

Timing copy number gains using point mutations. The relationship between point mutations and surrounding copy number gains can be used to infer the time of the gain. a Timing copy-neutral loss of heterozygosity (CNLOH). Blue mutations occurred prior to the CNLOH event, orange mutations occurred afterwards on either chromosome. b Gains of a single allele, where the other is retained, are more complex because single copy mutations can reflect both mutations that have occurred since the gain, and those on the non-duplicated allele (yellow)